Merge pull request #1 from vikeshkhanna/master

Adding editor files.
- Reorganizing the directory structure. server, instrumentor, and editor are now all under src/main/java/stanford/infolab/debugger/ subdirectories of a top directory named backend.
- Adding a pom.xml for the backend directory. (We're starting to use maven.)
- Adding a protocol buffer for scenarios. For now contains a GiraphScenario message that contains an ID, a set of msgs, and a list of neighbors.
- Adding a simple java file under utils that spits out a simple GiraphScenario.
- Adding vertex value to scenario.proto and changing GiraphTestScenarioWriter to write a dummy text as the vertex value.
Merge branch 'master' of https://github.com/semihsalihoglu/distributed_graph_debugger
Merge branch 'master' of https://github.com/semihsalihoglu/distributed_graph_debugger

First upstream merge.